Interest in the health effects of atmospheric particulate matter (aerosols) has increased, and the development of devices for analyzing the composition and behavior thereof is being studied in various quarters.
Aerosol mass spectrometers have recently been developed as a device for analyzing particle components, and are being utilized in the compositional analysis of particulate matter in the atmosphere and other environments. An aerosol mass spectrometer is a device for taking in a gas comprising particles inside a vacuum chamber from a space to be assessed, and measuring particle composition by collecting and thermally vaporizing the particles. In an aerosol mass spectrometer of this type, particles must be guided into a vacuum chamber, and these particles must be collected in a collection/thermal vaporization unit inside the chamber. As means for achieving this, for example, particle beam forming means such as that illustrated in FIG. 16 is used (refer to Patent Document 1). This particle beam forming means 100 comprises a prefocusing structure 114 having an internal orifice structure, and a tubular structure 118 having at least one primary focusing means 120 for forming a particle beam downstream from the prefocusing structure. The tubular structure 118 captures gas-dispersed particles from a particle source 112, and a particle flow is linearly formed by flow control in accordance with the internal prefocusing structure 114 and primary focusing means 120. That is, a gas component 112a having a higher lateral diffusion rate than the particles 112b is retained inside the tubular structure 118 and a vacuum chamber 132 and evacuated via an exhaust port 134 of the vacuum chamber 132, while the particles 112b maintain straight-line mobility and are ejected as a particle beam from a hole disposed in a partition 130 of the vacuum chamber 132. Particles are collected by causing this particle beam to collide with a collector disposed in a mass spectrometry unit, and the particles are thermally vaporized and guided to a detector, thereby making mass spectrometry of atmospheric particles possible, and enabling the analysis of the chemical composition of the particles.
This technology is not merely directed toward analyzing the chemical composition of particles; it is also used in semiconductor manufacturing and other such fields. For example, in Patent Document 2, a nanoparticle-containing gas for modifying the surface of a semiconductor is sprayed and specific particles are deposited onto a semiconductor substrate using the technology of Patent Document 1 to change the functionality and properties thereof. Technology for introducing such particles into a chamber (vacuum) and allowing them to converge within a certain range is of prime importance in measuring and manufacturing technologies.